In his new book Defending Your Castle, William Gurstelle shows you how to build catapults, crossbows and all the other devices you need to keep the invading hordes at bay. For this project to work ...
Two teams of kids design and build catapults to fling a tennis ball as far as possible. Two teams of kid engineers design and build catapults to fling a tennis ball as far as possible.
Some results have been hidden because they may be inaccessible to you
Show inaccessible results
Feedback